Maintenance monitoring devices which are arranged on installations such as machine tools are known such as, for instance, from the European publication EP-B-O 026 869. The time intervals of the operation of such machines which are relevant regarding the maintenance are registered by such maintenance monitoring devices. After expiration of pre-set maintenance time intervals within the mentioned maintenance relevant interval of the operation, a respective signal which is specific regarding the maintenance interval is emitted, for instance, for a lubrication of a first kind after 100 hours of operation, for lubrications of a second kind after 150 hours of operation, etc. After the maintenance work has been completed the corresponding displays are re-set and the mentioned maintenance time intervals are also re-set such that, after the maintenance within the frame of the maintenance relevant interval of operation they start to run cyclically anew.
These monitoring systems for the maintenance of installations have proven to be good.
However, in production plants having a plurality of machines to be monitored, one of these mentioned maintenance monitoring devices must be arranged at each such machine and there is the demand to obtain, such as for the planning of the maintenance, for the calling of maintenance teams, the appropriate of corresponding auxiliary material for the maintenance such as lubricants, etc. an overview over the complete state and demands, respectively of the maintenance of all installations and machines respectively.
From the British specification GB-A-2 142 172 it is known to selectively monitor electronic modules of an electronic plant and to store and emit maintenance information regarding the modules. Because all modules of the plant are simultaneously put into operation and switched off, respectively to which end energy is centrally switched to the plant and switched off, respectively the here represented procedure cannot satisfy above demands: this known maintenance technique corresponds to a maintenance monitoring device of a kind basically known from the European specification EP-B-0 026 869 applied to an electronic plant having various plant modules.
From the US-specification U.S. Pat. No. 4,688,183 a plant is known by means of which the most different data can be recorded and monitored, respectively at a building which allow to proceed with repair work at the correct time. A plurality of sensors structured to correspond to the data to be recorded are foreseen at the building which, organized hierarchically, are finally fed to a central unit. Because it is not foreseen to monitor at one and the same operation plant of the building such as at an elevator a plurality of different mutually overlapping maintenance intervals the entire building is here basically to be considered as an in-an-entirety operated plant corresponding to the monitored plant according to the EP-B-0 026 869 and the technique disclosed here can also not satisfy the above mentioned demands.
From the German specification DE-OS 28 23 558 a maintenance monitoring computer for machine plant is known which is employed similar to the monitoring device according to the EP-B-0 026 869, and thus operates at the level of operating plants and is not in a position to satisfy the above demand for a plurality of such plants.